Patent GB-1491322-A (GB)
Title: Value computing scale
IPC: G01G19/415
Filed: 1975-01-20
Abstract: 1491322 Weighing apparatus RELIANCE ELECTRIC CO 20 Jan 1975 [18 Jan 1974] 2388/75 Heading G1W A computing and weighing scale comprises computing means 15 including a sequence controller 19, weighing scale means 11 and data input means 17  for supplying weight and price data to the computing means which computes a value therefrom, printer means 21 for printing weight and price data and the computed value, said sequence controller controlling the value computation and the supplying of value data and the weight and price data to the printer means, digital weight display means 22 operatively connected to the computing means, and multi-plexing interface means 16 under the control of the sequence controller for multiplexing weight data from the scale means and price from the data input means and for supplying such multi-plexed data to the computing means and for receiving data from the computing means and supplying such data to the printer means and the digital weight display. The computing means, Figs. 4A, 4B, 4C, is an integrated circuit microcomputer and comprises a central processing unit 186 and a sequence controller consisting of a random access memory 187 and read only memories 188-192. Input data is multi-plexed on to busses 196 by means of a decimal to binary decoder 202 and four 8 line to 1 line decoders 198-201, and output data for the printing means and the weight display are stored in random access memory 228 under the control of address selector 229. The microcomputer calculates the net weight of an article and its value and causes these quantities and the price per unit weight to be printed out on a label at 21. Unit 17 Fig. 3 comprises switch busses 155 connected to the interface means 16 and a series of switches for connecting various strobe signal lines from the computer to selected ones of the busses. The tare weight of a container may be entered manually by means of switches 165, 166. When one of the manual tare switches is pressed the computer sums up the values of the switches pressed in a three second period and places this value into the tare memory. "Auto tare" and "no tare" switches 170, 171 respectively allow the computer to automatically tare or apply zero tare to the weighing. The price per pound may be applied to the computer either by manual switches 159-161 in unit 17. Alternatively, when switch 174 in unit 17 is pressed, the price is supplied automatically from the printer unit 21 which reads a digital code on a commodity plate inserted in the printer, the plate also carrying raised type for printing the article name. The printer may be controlled by switch 172 in unit 17 to print a label for each weighing, to print a new label each time a label is removed, or to print labels continuously. An automatic zero action is provided, a zero light  indicating when the zero is within “ of the least significant displayed digit. Unit 17 contains a  switch 177 which inhibits the auto zero action, and a captive range expand switch which allows zero errors up to 0À6 lb to be accumulated in a register. A zero expand switch 178 moves the decimal point one place to the left to increase the sensitivity by a factor of ten. The computer is arranged to prevent the printing of a label if a previously printed label has not been removed from the printer, if a previously weighed object has not been replaced, or if the maximum weight capacity or maximum value capacity has been exceeded. If the price per lb or tare value has been changed from a previous weighing, a lock switch 179 in unit 17 must be actuated before a label is printed. The printer includes printing wheels provided with commutators producing digital signals representing the positions of the wheels, and printing of a label is inhibited if these signals are incorrect. A service switch allows the price per lb or value stored in the computer to be displayed on display 22 to determine whether or not an error in a printed label is caused by the printer. Blanking switches are provided whereby any of the net weight, price per lb and value print outs may be inhibited manually. The computer and printer may also be used to print labels according to number rather than weight by operation of switch 172 in unit 177.